1. Field of the Invention The present invention relates generally to utility trench systems, and in particular to utility trench covers and their manufacturing methods.
2. Description of the Related Art
Utility trenches are used in civil engineering for concealment and protection of infrastructure, such as electrical conduit, electrical and communication cabling, piping, and other utilities. Utility trenches are often created by excavating the earth and placing the infrastructure within a trench enclosure or liner. Such trench enclosures can be constructed on-site or pre-fabricated for placement below grade.
A current type of utility trench system uses modular, pre-fabricated enclosures to protect the infrastructure and sectional covers or grates to cover the enclosures. Modular trench systems can comprise a series of pre-fabricated enclosures arranged longitudinally end-to-end in an excavation area and topped off with a cover. Such enclosures have been widely adopted because of the speed with which then can be installed and because they provide easy access to the infrastructure enclosed therein. Access to the enclosure is expedited by merely removing the sectional enclosure cover.
The enclosures and covers are commonly manufactured using materials that are suitable for their locations and expected uses. Reinforced concrete or masonry materials are often used for trench-lining enclosures. Enclosure covers are often manufactured using reinforced concrete or steel. The resulting enclosure covers can be strong and durable but very heavy. Strong enclosure cover design is important in particular applications in order to support heavy vehicular traffic. For example, electrical utility trenches are commonly used in such facilities as powerplants, electrical distribution substations, factories, etc. Service trucks and other vehicles commonly cross the trench lines and must be supported by their covers.
However, previous steel and reinforced concrete trench covers were cumbersome to remove when trench access was needed. Moreover, electrically conductive materials, such as metal, should be avoided in electrical utility installations due to electrical hazards. Trench enclosure covers should therefore preferably be strong, durable, weather-resistant, non-conductive and lightweight. Installation and removal operations and trench-access procedures should not require multiple personnel and/or hoisting equipment. Moreover, they should be adaptable for both constructed on-site enclosures and pre-fabricated enclosures. Scalability can also be an important consideration in trench enclosure design because trenches of various dimensions can be accommodated with a basic cover design. The present invention addresses these design criteria. Heretofore there has not been available a utility trench cover with the advantages and features of the present invention.